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Post by waynelawkid on Oct 31, 2017 16:15:46 GMT -7
I'm hoping to get some guidance from the Z masses on an issue I've been having with my Z Lux combo. Recently, when playing through the amp it sporadically cuts to almost no volume. I'll be strumming away and suddenly it cuts to nearly no volume at all. When it first happened, I went to lightly tilt the amp forward to view the tubes and it went back to full volume. When it happened again, a light tap on the top of the amp brought the volume back.
I initially thought it was a bad tube so I pulled and tested ALL of them (Yes, V1 - V10) on my Conar tube tester. All of the tubes tested fine. I even swapped each of the 12x7 tubes (V1, V2, V4, V5, V6) with a known working 12ax7 and it still had the same behavior - it would sporadically lose nearly all volume, but a light tap on the amp brings it back to full volume. Finally, I lightly tapped each preamp tube with a pencil eraser and discovered that it is the phase inverter 12ax7 in V6 that seems to be the culprit. The slightest touch to the tube causes the amp to basically cut out. Another touch brings it back. I swapped in another good 12ax7, and it did the same thing.
Thoughts? Short in the V6 socket?
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Post by j4gitr (John) on Oct 31, 2017 16:45:38 GMT -7
Did you rule out cables?
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Post by waynelawkid on Oct 31, 2017 17:52:20 GMT -7
Yes. I even checked the input jack on the Les Paul I was using for the test to make sure it wasn't causing intermittent failure. I'm 99.9% sure it's something with V6 given the fact that I can cause the failure at will by ever-so-lightly touching the tube.
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Post by zpilot on Oct 31, 2017 20:56:00 GMT -7
Not a "short". It sounds from your description like a failed solder on that socket which would be an "open". Excuse me for being technical.
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Post by purpletele on Oct 31, 2017 21:43:02 GMT -7
I agree with Z Pilot.
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Post by BritInvasion on Nov 1, 2017 6:41:15 GMT -7
Not a "short". It sounds from your description like a failed solder on that socket which would be an "open". Excuse me for being technical. ^^ This.
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Post by bgkyt1 on Nov 1, 2017 6:53:27 GMT -7
that happened to me on an older used amp and it was a worn out (enlarged) socket pin. being this is a newer amp, i wouldn't think that would be the case. if you take the tube out, see if the socket's pins all look the same.
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Post by zpilot on Nov 1, 2017 7:47:21 GMT -7
I understand that there were some tubes being sold at one time that had pins that were smaller in diameter than what is normal. That's not something that would be the case with the stock tubes but if they have been changed you might have one of those. I don't know what brands are an issue but I think JJ was one. If they are smaller they might not match the sockets and the sockets would need to be re-tensioned.
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Post by waynelawkid on Nov 1, 2017 17:14:36 GMT -7
Thanks for all the feedback and helpful info, folks! I went ahead with the least intrusive tip above and re-tensioned the pin sleeves in the V6 socket. Played it for an hour without issue. I can now tap the V6 tube without it cutting in and out. Keeping my fingers crossed that this is a fix and not a band-aid.
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